Watts Amperage Calculator
Calculate power (watts), current (amps), or voltage (volts) using Ohm's law. Enter any two values to compute the third.
Published by:
isCalculator Editorial Team
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How to use this tool?
This calculator uses Ohm's Law to find the missing electrical value. Enter any two of the three fields below, and it will calculate the third.
- Enter two values – Fill in any two of the three inputs: Voltage (V), Current (A), or Power (W). Leave the third field empty.
- Click "Calculate" – The result will appear instantly, showing the missing value and the formula used.
- Interpret the result – The output is displayed with the correct unit (V, A, or W). A brief formula explanation is shown below the result.
- Reset if needed – Use the "Reset" button to clear all fields and start over.
- All values must be positive numbers (no negatives).
- If calculating voltage, current cannot be zero. If calculating current, voltage cannot be zero.
- No unit conversion is needed – just enter the values as they are (e.g., 120 for volts, 10 for amps).
Important notes:
Previous Results
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Frequently Asked Questions
Enter any two values among voltage (volts), current (amps), and power (watts). The calculator will compute the missing value using Ohm's law (P = V × I).
The calculator requires exactly two inputs. If you enter three, it will prompt you to leave one field empty.
Yes, you can enter decimal numbers for precise calculations.